The application relates to a hearing device configured to be placed in the ear canal of a user, the hearing device comprising a forward path adapted for processing an input sound and providing an output sound representative of the input sound, the hearing device comprising an assembly comprising first and second modules adapted for being in mechanical contact with each other when the hearing device is operationally assembled to form a functional unit. The object of the present application is to provide a user friendly hearing device adapted for being located in an ear canal of the user. The problem is solved in that the first module comprises a power supply unit, and the second module comprises an input unit, a signal processing unit and an output unit in operational connection, wherein the first and second modules are configured to provide that the first and second modules are reversibly attachable to and detachable from each other; and the first and second modules are electrically connected to provide that units of the second module are energized by the battery of the first module, when the first and second modules are operationally assembled. This has the advantage of providing relatively simple and easy to use hearing device. The invention may e.g. be used for hearing aids, in particular extended wear hearing aids adapted for being located deep in the ear canal of a user.